1. Field of the Invention
The present invention relates to a shutter drive device for a camera.
2. Description of the Related Art
Conventionally, an electromagnetic actuator is employed as a driving source of a shutter blade for a camera (see Japanese Unexamined Patent Application Publication No. 2005-173355). FIG. 5 is a cross-sectional view of a conventional shutter drive device for a camera in which an electromagnetic actuator is employed as a driving source. Such a shutter drive device for a camera includes: an electromagnetic actuator; an upper plate 160 and a lower plate 150 supporting the electromagnetic actuator and each having an opening (not shown) for shooting; and shutter blades 170 to 173 disposed between the lower plate 150 and a blade supporting plate 180. The electromagnetic actuator includes: a coil 140 for excitation; a rotor 120 magnetized with different magnetic poles in a circumferential direction; a spindle 152 supporting the rotor 120 for rotation; a stator 110 excited with magnetic force relative to the rotor 120 by energization of the coil 140.
The rotor 120 is provided with a outputting member 130 which rotates in conjunction with the rotor 120. The outputting member 130 is provided with a pin portion 131. The pin portion 131 outputs the driving force of the rotor 120 to the shutter blades 170 to 173. This causes the shutter blades 170 to 173 to open and close the opening for shooting. In addition, the lower plate 150 and the blade supporting plate 180 which define a blade chamber are provided with opening 151 and 181, respectively. The openings 151 and 181 receive the rotation of the pin portion 131.
However, in such a shutter drive device for a camera, the shutter blades overlap with each other in a rotational axis of the rotor 120. This increases the thickness in the axial direction of the rotor 120. Therefore, in an electronic apparatus employing such a shutter drive device for a camera, degrees of freedom of the layout of electronic components is limited. Further, the lower plate 150 and the blade supporting plate 180, which define the blade chamber, respectively have the opening 151 and 181 for receiving the rotation of the pin portion 131, and these openings are the second longest after the opening for shooting. Therefore, this may allow dusts to enter the blade chamber via the opening for receiving the rotation of the pin portion 131. The entering dust may affect on the actions of the shutter blades.